There's also the problem that, of the few that do put 'Compatible with
Linux', far too many of them are doing so only because they've heard
that Linux is the up-and-coming OS, but haven't taken the time to learn
anything about it and think that all they have to do is recompile their
Mac drivers on a Linux box (because MacOS is kind of Linux-ish, isn't
it? Yes, I really have had that said to me and, I'm afraid to say, I
just couldn't be bothered to try and explain why it really, really
isn't), rather than re-write them from the ground up for the Linux kernel.

And then they get all annoyed that they get complaints from Linux users
about their hardware and stop 'supporting' it.

I have learned the hard way, I'm afraid, not to trust *anything* the
manufacturers say about their hardware's Linux compatibilty (I have had
both 'Linux compatible' hardware that wasn't and most emphatically *not*
Linux compatible hardware that worked perfectly) and to research
thoroughly anything I want to buy.